Composite structures such as those used in the aerospace industries may be fabricated using automated fiber placement (AFP) machines that lay down relatively narrow strips of pre-impregnated tows or slit composite tape onto a manufacturing tool, such as a mandrel. AFP machines may include one or more tape application heads that simultaneously lay down a group of tows arranged side-by-side as a conformal band onto the tool. The tows are pulled from storage spools or creels carried on the placement head and are fed to one or more compaction rollers that apply and compress the tow band onto the tool or substrate surface.
The pre-preg tow being dispensed from a supply spool comprises a series of segments that are spliced together end-to-end by pressing the ends of the tow segments together. Since the fibers are not continuous at the location of a splice, a tow may be somewhat inherently weaker at the splice. However this weakness is not a defect and does not normally present a problem unless the splices in the laminate plies became undesirably aligned through the thickness of the structure. Alignment of splices through the laminate may affect the load bearing capability of the laminate structure, and thus are to be avoided if possible. Material suppliers often identify the location of splices in a tow by applying visible markings on the splice. While these markings visually identify the location of the splices along a tow and may be used in making a rough estimate of the number of splices in a laminate, it is not presently possible to determine when and where the splices may become aligned through the thickness of the laminate.
Accordingly, there is a need for a method and apparatus for 3-D mapping and displaying of the locations of splices within a laminate in order to allow visualization of potentially undesirable alignment of the splices.